Figure 7.

Neuronal injury evaluated at 48 h after asphyxia in the different cortical and subcortical regions. (A): In the neocortex, neuropathology scores suggested that asphyxia-induced neuronal injury was mitigated by hypothermia; however, there were no statistically significant differences among the groups (lines, boxes, whiskers, and bullets represent the median, the interquartile range, the 10th-90th percentiles, and raw data, respectively). (B–F): In the other assessed regions, cell counting revealed no significant differences in the low percentage of damaged neurons between the naïve and control-normothermia (C-NT) groups. Compared to the C-NT group, severe neuronal damage was detected in virtually all areas in the groups that were subjected to asphyxia. Neuronal damage was similar in both the CA1 and the CA3 hippocampal subfields in all groups exposed to asphyxia, despite hypothermia treatment. However, in the asphyxia-hypothermia (A-HT) group, a significant decrease in percentage of damaged neurons in the caudate nucleus was observed compared to the asphyxia-normothermia (A-NT) group, and there was a similar tendency in the putamen and the thalamus. Importantly, co-treatment with H₂ or CO₂ to achieve graded restoration of normocapnia did not augment the hypothermia-induced neuroprotection (A-HT + H₂ and A-HT + CO₂ groups, respectively). Instead, a significant increase in neuronal damage was observed in the caudate nucleus in the A-HT + CO₂-treated group compared to the A-HT group. Data are mean ± SEM; bullets represent raw data, * vs. A-NT; † vs. A-HT, p < 0.05; statistical significance from naïve or C-NT groups is not shown. Representative photomicrographs are shown in Supplementary Figures S1–S5.